All the feast and Holy days were written for the Israelite while they were in the desert for forty years. no other nation had heard of these feast and holy days. there were some outsiders in the camp also known as strangers, and they were not allowed to participate in any, only the Israelites. these were not just for the Jews, but all Israelites. The gentile were only to hear the gospel Of Jesus Christ and believe on his name and be saved. Jesus never said they had to follow any of theses.